Source: Purdue Extension

Excessive heat and humidity this time of year probably is taking a toll on corn yields, explained Purdue Extension Agronomist Tony Vyn.

With corn development well ahead of normal, high temperatures will mean an early maturity and harvest. Had drought occurred, yield losses would have been more severe, but just because there'bs been no drought in 2010, above trend-line yields are not guaranteed, Vyn said.

Daytime temperatures up to 86 F are beneficial for corn plant photosynthesis. Anything above 86 F for a sustained amount of time can foster disease development, cause stress during grain fill and exacerbate ear rots.

"Leaf diseases are more likely to spread in high humidity situations," Vyn further said. "On susceptible hybrids and in fields not sprayed with effective fungicides, the leaf area available for photosynthesis during the critical grain filling period can decline too rapidly. Corn plants also are more susceptible to stalk rot infection with high humidity and wet surface soils."

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